A related patent application is a commonly assigned Japanese Patent Application No. 2002-36457 filed on Feb. 14, 2002, which is incorporated by reference into the present patent application.
1) Technical Field of the Invention
The present invention relates to a power semiconductor device for controlling a substantial amount of current used for electrical systems such as a motor and a heater.
2) Description of Related Arts
Recent industrial systems incorporated in an electric car and an elevator, in particular, have been improved in smooth motion and comfort for ride. This improvement comes significantly from contribution of power semiconductor devices that control the power (current) of such systems. In the power semiconductor devices, a substantial amount of heat is generated, which should efficiently be radiated outside of the power semiconductor device, for example, by using a radiating fin.
Referring to FIGS. 8 through 10, a conventional power semiconductor device will be described hereinafter. A power semiconductor device 101 shown in FIG. 8 includes, in general, a housing 110 made of insulating material such as resin and a base plate 130 made of metal of a good thermal conductivity such as copper. The housing 110 has a bottom surface fixed on the base plate 130 by means of metal screws or adhesive (not shown). As shown in FIG. 9, the power semiconductor device 101 also includes a plurality of main terminals 111 extending from an upper surface to an inside portion of the housing 110. The device 101 also includes an insulating substrate 115 with patterned metal layers 114a, 114b formed on both sides thereof, and a power semiconductor chip 120 mounted on the upper metal layer 114a by means of solder 116. The power semiconductor chip 120 is supplied with electric power from the main terminals 111 through a plurality of metal wires 123 of metal such as aluminum. The lower metal layer 114b of the insulating substrate 115 is bonded on the base plate 130 through a solder 117.
In the power semiconductor device 101, for protection of the semiconductor chip 120, silicone gel 124 (the hatching thereof not shown for clarity) is filled over the semiconductor chip 120 and the insulating substrate 115. The silicone gel 124 is then sealed by epoxy resin 125 deposited thereon. Lastly, a cover 126 is formed on the epoxy resin 125.
When the power semiconductor device 101 so constructed is assembled within a peripheral device, a plurality of bus bars 140, each of which is an external conducting plate (also referred to as xe2x80x9cconducting memberxe2x80x9d), are arranged on and connected with the main terminals by means of metal screws 145, as shown in FIG. 9. Also, in the power semiconductor device 101, in order to efficiently radiate undesirable heat generated by the semiconductor chip 120 outside of the power semiconductor device 101, the base plate 130 is required to closely contact with a radiating fin 150 by means of a plurality of metal screws 147, as illustrated by imaginary lines of FIG. 9. Therefore, according to the power semiconductor device 101, the base plate 130 needs four through-holes 148 formed at each corner thereof for receiving metal screws 147 so as to closely contact with the radiating fin 150.
However, when the metal screws 147 are used to secure the base plate 130 on the radiating fin 150, the housing 110 can not be extended beyond the space over the through-holes 148 of the base plate 130. Thus, unavailable dead spaces are defined over the through-holes 148, thereby preventing the power semiconductor device 101 from downsizing. As clearly illustrated in FIG. 8, in the actual assembly of the power semiconductor device 101 to the peripheral device, four screws 145 are required to connect two pairs of bus bars 140 with the corresponding main terminals 111. And as above, another four screws 147 are essential to closely contact the base plate 130 with the radiating fin 150. It is almost impossible to reduce the number of parts (screws) and tasks required for assembly.
The present invention has an object to provide a more compact power semiconductor device, in which the base plate and the radiating fin can be secured without defining any dead space.
Also, the present invention has another object to provide the power semiconductor device that can be assembled with reduced parts and tasks, in which close contact between the base plate and the radiating fin can be achieved simultaneously with connection between the bus bars and the main terminals.
Further, the present invention has another object to provide the power semiconductor device, which eliminates the base plate.
In particular, the present invention is to provide a semiconductor device, which includes a housing having a top and bottom surfaces, and an insulating substrate with metal layers formed on both sides thereof. The insulating substrate is surrounded within the housing. A semiconductor chip is mounted on one of the metal layer of the insulating substrate. Also, a terminal connector extends along the top surface of the housing and is bent towards the bottom surface thereof for supplying the semiconductor chip with power. In the semiconductor device, the housing has a housing through-hole extending from the top surface to the bottom surface through the housing, and also the terminal connector has a terminal through-hole which are aligned with and formed coaxially with the housing through-hole.
Therefore, a fastening member (screw) extending through the housing through-hole and the terminal through-hole can be used to fasten the semiconductor device with a metal radiator, and at the same time, to realize an electrical connection between a conducting member and a terminal connector. Thus, total time required for assembly with peripheral devices and for connection between the conducting member and the terminal connector can substantially be reduced. Also, the undesirable dead spaces of the prior art are eliminated and number of parts is reduced so that the power semiconductor device of the present invention is more compact, simpler in structure, and less expensive to manufacture than the conventional power semiconductor device.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the sprit and scope of the invention will become apparent to those skilled in the art from this detailed description.